Moody's also affirmed its "Aa3" senior debt rating on Mercury General, and its "Aa3" insurance financial strength ratings on the company's Mercury Casualty Co. and Mercury Insurance Co. units.
Moody's said it expects Mercury, which is based in Los Angeles, will maintain its underwriting profitability given its strong position in the California personal auto market and its conservative debt levels.
The company has also implemented a number of cost-control measures in other parts of its business, which Moody's said it expects will limit its risks.